The present invention relates to the field of organic chemistry and more specifically to the preparation of methyl N-methylanthranilate.
At least two processes for the preparation of the subject compound are known in the prior art. In one such process anthranilic acid is used as the starting compound and reacted with formaldehyde and hydrogen as described in J. Soc. Org. Synthetic Chem. (Japan) 11,434 (1953), Chem. Abst. 49, 955a (1955), to produce N-methylanthranilic acid. This resulting intermediate is thereafter reacted with thionyl chloride and methanol to produce the desired methyl N-methylanthranilate. This step is described in Aust. J. Chem. 27, 537 (1974). The disadvantages of this process lie in the use of a relatively expensive starting material and the relatively poor yields of final product. Typical reported reaction yields based on the starting compound amount to about 36% overall for the two steps.
In another prior art process, described in J. Org. Chem. 24,1214 (1959), the starting compound is N-methylisatoic anhydride, again a costly starting material which is more expensive than anthranilic acid.
Methyl N-methylanthranilate has found use in the preparation of artificial food flavorings. The compound has been disclosed to be offensive to birds and has "very excellent repellent action for prolonged periods in very small concentrations" according to U.S. Pat. No. 2,967,128 which issued on Jan. 3, 1961.
It is an object of this invention to provide a process for the preparation of methyl N-methylanthranilate which is feasible towards producing the compound in commercial quantities, in high purity and good yield.